For example, there happens a case where fine wood chips or shavings are found to be left on base sheets of floor materials during work of driving nails into the base sheets when making a floor. When finishing materials are laid over the base sheets with those fine wood chips or shaving left thereover as they are and then driving nails into the base sheets, the finishing materials are nailed down while being partially separated from the base sheets due to the wood chips or shavings left on the base sheets, resulting in floor making work having to be performed again. In order to prevent the occurrence of such inconveniences, finishing materials were set after surfaces of base sheets had been cleaned by an air duster for nailing work. However, since the air duster was provided separately from the nailing machine, when a large number of finishing materials were nailed down, since the nailing machine and the air duster had to be handled alternately, the nailing work was very troublesome.
Then, as a means for eliminating these inconveniences, there have been known nailing machines having an air duster provided thereon (refer to Patent Document 1). According to such nailing machines, since the nailing machine and the air duster do not have to be handled alternately every time wood dust has to be removed, the nailing machine with the air duster is convenient in this respect.    Patent Document 1: Japanese Patent No. 3385875    Patent Document 2: JP-A-2004-1135    Patent Document 3: JP-A-2004-1136
However, the aforesaid air duster fitted nailing machines had the following drawbacks. (1) An operating part for the air duster is provided on the body, so that an actuation trigger lever can be operated at the same time as the air duster is being used. In addition, since a construction is adopted in which compressed air for the air duster is taken out from a main chamber (an accumulating chamber) for nail driving, when the air duster operating part and the trigger lever are operated at the same time, the nailing machine is driven in such a state that the main chamber is at low pressure, thereby causing problems that nail driving failures occur due to insufficient outputs and that a driving piston cannot be returned to its initial position. (2) Since the construction is adopted in which compressed air for the air duster is taken out from the main chamber, oil supplied to a nailing machine main body and containing dirt in an engine part is discharged together with the compressed air from a nozzle, and the dirty oil so discharged adheres to finishing materials, whereby the finishing materials become dirty. (3) In particular, in the case of highly pressurized air, since air pressure discharged is high, there is caused a fear that wood chips or shavings may be blown up more than necessary. Because of this, there are nailing machines in which a pressure reducing valve is installed in an air duct which communicates with the nozzle (refer to Patent Document 3). However, this increases the number of components and configures major factors for increase in the weight and production costs of the nailing machine. (4) Since a button for the air duster and the actuation trigger lever of the nailing machine are positioned relatively close to each other, nailing work can be performed while using the air duster, leading to a danger of occurrence of an accident.